The need for observational HIV clinical research to complement the invaluable information provided by randomized controlled trials has grown tremendously, which is why we established the CFAR Clinical Epidemiology and Health Services Research (CE&HSR) program at the University of Washington (UW) in 1997 and were among the first CFARs in the US to do so. The UW CE&HSR Core pioneered approaches to standardization, content, and integration of clinical HIV data required for HIV/AIDS research and has become a key engine for cohort-based health research locally, nationally, and internationally, which has had tremendous impact on the field and on the clinical care and outcomes of HIV-infected individuals. The UW/FHRC CFAR CE&HSR Core will address the following specific aims: Aim 1. Facilitate Comparative Effectiveness Research to Improve HIV Disease Outcomes: promote and support HIV/AIDS clinical research comparing the effectiveness of treatment strategies for HIV-infected patients in routine clinical care, including the management of serious HIV-associated chronic diseases, such as cardiovascular, renal, and liver disease with the goal of improving HIV disease outcomes. The Core is forming Chronic Disease Study Groups to develop analysis plans for defining and validating data needed to conduct research in the areas of HIV-related pulmonary and neurological complications, cardiovascular, liver and metabolic diseases, and determining the impact of socio-behavioral conditions and HIV-related disparities on clinical outcomes. We will continue to train junior investigators and recruit investigators from other disciplines who are new to HIV research to collaborate in addressing emerging questions regarding HIV/AIDS. Aim 2. Expand the UW HIV Information System (UWHIS): provide a wide range of research expertise and a comprehensive source of prospective, longitudinal patient data capturing rapidly changing HIV treatment and outcomes to support innovative interdisciplinary HIV/AIDS research. We will promote collaboration between clinician researchers, epidemiologists, biostatisticians, basic scientists, socio-behavioral and health services researchers using novel approaches to address the most pressing questions concerning HIV/AIDS treatment and prevention. Aim 3. Facilitate Translational and Basic HIV Research: support translational and basic research aimed at defining the underlying pathogenesis of chronic inflammation in HIV and mechanisms leading to chronic end organ disease by expanding clinical specimens collected on the UW HIV Cohort tracked in the UWHIS linked to patient data and stored in the UW HIV Specimen Repository.